Apparatus and method for the detection and treatment of atrial fibrillation

ABSTRACT

Embodiments of the invention provide methods for detection and treatment of atrial fibrillation (AF) and related conditions. One embodiment provides a method comprising measuring electrical activity of the heart using electrodes arranged on the heart surface to define an area for detecting aberrant electrical activity (AEA) and then using the measured electrical activity (MEA) to detect foci of AEA causing AF. A pacing signal may then be sent to the foci to prevent AF onset. Atrial wall motion characteristics (WMC) may be sensed using an accelerometer placed on the heart and used with MEA to detect AF. The WMC may be used to monitor effectiveness of the pacing signal in preventing AF and/or returning the heart to normal sinus rhythm (NSR). Also, upon AF detection, a cardioversion signal may be sent to the atria using the electrodes to depolorize an atrial area causing AF and return the heart to NSR.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/224,900, filed Mar. 25, 2014, which is a continuation of U.S. patentapplication Ser. No. 14/168,680, filed Jan. 30, 2014, which is acontinuation of U.S. patent application Ser. No. 12/757,865, filed Apr.9, 2010, now U.S. Pat. No. 8,731,662, issued on May 20, 2014, which is acontinuation of U.S. patent application Ser. No. 12/427,733, filed Apr.21, 2009, now U.S. Pat. No. 8,644,927, issued on Feb. 4, 2014. Theaforementioned priority applications being hereby incorporated byreference in their entirety for all purposes.

FIELD OF THE INVENTION

Embodiments described herein relate to an apparatus and method fordetection and treatment of atrial fibrillation. More specifically,embodiments described herein relate to an apparatus and method fordetection and treatment of atrial fibrillation using distributed bipolarelectrodes placed on the surface of the heart to detect the earliestonset of fibrillation.

BACKGROUND

The heart has four chambers, the right and left atria and the right andleft ventricles. The atria serve as primer pumps to the ventricles whichin turn pump blood to the lungs (the right ventricle) or the aorta andthe remainder of the body (the left ventricle). The heart is essentiallyand electromechanical pump, which contracts and pumps blood by means ofa wave of depolarization that spreads from the atria to the ventriclesin a timed fashion through a series of conduction pathways. Cardiacarrhythmia is a condition afflicting the heart and is characterized byabnormal conduction patterns which in turn can affect the pumpingefficiency in one of more chambers of the heart. It can occur in eitherthe atria, ventricles or both. Particular types of Atrial arrhythmia cancause a condition known as atria fibrillation (AF) in which the pumpingefficiency of the atria are compromised. Instead of contracting in acoordinated fashion, the left or right atria flutter with little or nopumping efficiency.

During an episode of AF, the normal electrical impulses that aregenerated by the sino-atrial node (the SA node), the natural pacemakerof the heart are overwhelmed by disorganized electrical impulses, knownas ectopic foci that may originate in the atria or pulmonary veins,leading to conduction of irregular impulses to the atria and theventricles. This can result in an irregular heartbeat, known as anarrhythmia which may occur in episodes lasting from minutes to weeks, oryears. Left unchecked, AF often progresses to become a chroniccondition.

Atrial fibrillation is often asymptomatic, and while not immediatelylife-threatening, may result in palpitations, fainting, chest pain(angina), or congestive heart failure. Patients with AF have asignificantly increased risk of stroke and pulmonary embolism due to thetendency of blood to pool and form clots or emboli in the poorlycontracting atria which are then sent to the lungs in the case of theright atria causing pulmonary embolism, or the brain causing stroke.

Atrial fibrillation may be treated with medications, implantedventricular defibrillators or surgical procedures. The currentmedications used either slow the heart rate or revert the heart rhythmback to normal. However patients must remain on medication for life andmany patients cannot be successfully treated with medication. Implantedventricular defibrillators may be used to deliver a series of highvoltage electric shocks to convert AF to a normal heart rhythm in atechnique known as synchronized electrical cardioversion. However, theseshocks are extremely painful and may cause the patient to pass orliterally be knocked to the ground from the shock. Surgical andcatheter-based therapies may also be used to ablate or destroy portionsof the atria and pulmonary veins containing the ectopic and other fociresponsible for the generation of arrhythmias causing AF; however theserequire open heart surgery, cardiac catheterization or both and have metwith limited success. Thus, there is a need for improved methods anddevices for the treatment of atrial fibrillation.

BRIEF DESCRIPTION

Embodiments of the invention provide apparatus, systems and methods forthe detection and treatment of atrial fibrillation and relatedconditions. Many embodiments provide a system including a pacemakercoupled to endocardial and/or epicardial leads having a distributedpattern of bipolar electrodes for the early detection and treatment ofatrial fibrillation.

In a first aspect, the invention provides an endocardial lead havingmultiple bipolar electrodes that attach to the endocardial surface ofthe right atria in a distributed pattern for the early detection andtreatment of fibrillation in the right atria. Preferably, the electrodesare arranged in a circular or other pattern on the endocardial surfaceof the right atria to define an area for detecting the location of afoci of aberrant electrical activity causing onset (including earlieronset) of atrial fibrillation. In specific embodiments, the foci can bedetected by an algorithm in the pacemaker which identifies the locationon the endocardial surface (by the nearest electrode pair) having theearliest activation (i.e., depolarization) during an episode of AF.

Once a foci is detected, the electrodes nearest the foci can then beused to send a pacing signal at that site to prevent the site fromcausing atrial fibrillation. In some embodiments, that site of earlyactivation can be paced continuously. The lead is coupled to a pacemakerto send sensed signals from each electrode pair back to the pacemakerelectronics for analysis to determine the onset of atrial fibrillationor a signal predictive or the onset of atrial fibrillation. The lead canbe positioned by in the right atria by introduction and advancement fromthe jugular vein using cardiac catheterization techniques known in theart.

In particular embodiments, the electrodes can be positioned in acircular, oval or related pattern around the SA node. The electrodepairs can be positioned on a circular or oval shaped patch that isattached to the endocardial surface using mechanical attachment elementsuch as a helical screw, barbed needle or other attachment means such asa biocompatible adhesive. The adhesive can comprise a thermallyactivated adhesive that is activated by heat from the body or resistiveheating from signals sent to the electrode pair. The patch can comprisea PTFE, polyester or other biocompatible material known in the art andis desirably configured to bend and flex with the motion of the heartwall. It may also include one or more nonthrombogenic coatings includingcoatings impregnated with various elutable drugs known in the art suchas TAXOL to prevent thrombus, platelet and other cell adhesion. Theelectrodes can comprise a radio-opaque or echogenic material forvisualizing a location of the electrodes in the heart under flouroscopy,ultrasound or other medical imaging modality. Also the patch can includea section made out of such materials to serves as a marker forvisualizing the location of the electrodes in the heart.

In a related aspect, the invention provides an epicardial lead havingmultiple bipolar electrodes that attach to the epicardial surface of theleft atria in a distributed pattern for the early detection andtreatment of fibrillation in the left atria. Preferably, the electrodesare arranged in a pattern on the epicardial surface of the left atria toelectrically map the atria so as detect the location of a foci ofaberrant electrical activity causing early onset of atrial fibrillationin the left atria. The pattern includes placement of one or moreelectrodes adjacent one or more of the pulmonary veins so as to detectfoci in these locations. Additionally, in left atria lead embodiments,the lead can also be coupled to a 3-axis accelerometer placed on theepicardial wall of the atria to sense atrial wall motion predictive ofatrial fibrillation and normal sinus rhythm. The signal from theaccelerometer may be used as a sole indication of AF, or it may be usedto supplement the electrical signals from the bipolar leads positionedon the left atria to increase the predictive power of various algorithmsused by the pacemaker for the detection of AF. Additionally, sensoryinputs from the accelerometer can also be used to assess theeffectiveness of atrial pacing signal in preventing AF and/or returningthe heart to normal sinus rhythm.

In another aspect, the invention provides an apparatus, system andmethod for performing low voltage distributed cardioversion forconverting the atria from a fibrillative state back to normal sinusrhythm. In these and related embodiments, the pacemaker cansimultaneously send a higher voltage pacing signal (in the range of 8 to10 volts) to all pairs of electrodes (e.g., on the particular atriallead) to stimulate a large enough area of the atria to eliminate thearrhythmia. By using voltages lower than those typically used duringexternal or internal cardioversion (which can be in the hundreds ofvolts for internal conversion to the thousands for external conversion)the pain experienced by the patient can be greatly reduced. The otherbenefit of this approach is that by using bipolar electrodes at eachsite, the electrical energy delivered to the heart can be contained in avery small region so that the risk of stimulating the ventricles (anunwanted effect in this case) is very small.

Further details of these and other embodiments and aspects of theinvention are described more fully below, with reference to the attacheddrawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral view showing an embodiment of a system for thetreatment of atrial fibrillation including a pacemaker and various leadsgoing to the atria and ventricles for AF detection and pacing andventricular pacing.

FIG. 2 is a cross sectional view of the heart showing the placement inthe heart of the various leads from the embodiment of FIG. 1

FIG. 3 is a side view of the right atria showing an embodiment of anatrial lead having a distributed pattern of bipolar electrodes placed onthe endocardial surface of the right atria for the detection andtreatment of AF.

FIG. 4 is a side view of the left atria showing an embodiment of aparallel atrial lead configuration connected to a distributed pattern ofbipolar electrodes placed on the epicardial surface of the left atriafor the detection and treatment of AF.

FIG. 5 is a cross sectional view showing an embodiment of an atrial leadfor sensing and pacing.

FIG. 6a is a top down view showing an embodiment of a bipolar electrodeassembly including a pair of bipolar electrodes positioned on a patch orother support layer.

FIG. 6b is a cross sectional view showing positioning of an embodimentof the bipolar electrode assembly on the endocardial wall.

FIG. 7 is a block diagram illustrating some of the typical circuitry ona pacemaker or other implantable pacing or stimulating device.

FIGS. 8a-8c are graphs showing an EKG for normal sinus rhythm (FIG. 8a )and during an episode of atrial fibrillation, including the ventricles(FIG. 8b ) and atria (FIG. 8c ).

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention provide apparatus, systems and methods forthe detection and treatment of atrial fibrillation and relatedconditions. Many embodiments provide a system including a pacemakercoupled to endocardial or epicardial leads having a distributed patternof bipolar electrode for the early detection and treatment of atrialfibrillation.

Referring now to FIGS. 1-2, an embodiment of a system 5 for thedetection and treatment of atrial fibrillation comprises a cardiac pacemaker or related device 10, and one or more leads 20 positionable in/onthe atria A and/or ventricles V of the heart H. Leads 20 can be coupledto pacemaker 10 by means of a multi-lead connector 12. In variousembodiments, leads 20 can include: a lead 21 positionable on theendocardial wall ENW of the right atria RA for sensing and pacing theright atria; a lead 22 positionable on the epicardial wall EPW of theleft atria LA for sensing and pacing the left atria, a lead 23positionable on the endocardial wall of the right ventricle RV forsensing and pacing the right ventricle and a lead 24 positionable on theendocardial wall of the left ventricle LV for sensing and pacing theleft ventricle.

Referring now to FIGS. 3-6, in various embodiments, leads 21 and/or 22can comprise an apparatus 30 for the detection and treatment of atrialarrhythmia. Apparatus 30 can comprise a lead 40 having proximal anddistal portions 41 and 42 and a plurality of electrode assemblies 50coupled to the lead. As is described below, electrode assemblies 50 aredistributed in a pattern 63 along lead 40 so as to define an area 60 fordetecting and locating a foci of aberrant myoelectric activity causingatrial fibrillation. Apparatus 30 including lead(s) 40, can beconfigured for placement in various locations in the heart including theright atria RA, as is shown in the embodiment of FIG. 3, or the leftatria LA, as is shown in the embodiment of FIG. 4. FIG. 4 also shows anembodiment of device 30 having a plurality 40 p of leads 40 coupled inparallel to electrode assemblies 50 and pacemaker 10. In these andrelated embodiments leads 40 can be coupled to a common connector 14,which can be the same as connector 12.

The proximal portion of lead 40 includes an end 41 e configured to becoupled to a pacemaker 10 or a related device. The distal portion 42 ofthe lead is configured to be positioned in an atrial chamber (right orleft) AC of the heart H. Lead 40 comprises an outer sheath 43surrounding a plurality of conductive wires 44 each having an insulativesheath 45 over all or a portion of their lengths. Conducive wires 44 cancomprise copper or other conductive metal known in the art. Desirably,lead 40 also has sufficient flexibility and pushability as is known inthe catheter arts to be advanced into the atrial chamber of the heartfrom a percutaneous introductory site such as the jugular vein in theneck or other like site.

In many embodiments, electrode assembly 50 comprises a pair 51 ofbipolar electrodes 52 which are disposed in or otherwise positioned on apatch 53 or other support layer or structure 53 that can be attached tothe heart wall. Electrode assembly 50 and electrodes 52 are configuredto sense electrical activity within a region of myocardial tissue MTwithin the heart wall HW of the atria to detect an ectopic or other fociF of abnormal electric activity and send a pacing signal 56 to the heartwall to depolarize region MT containing the Foci F. Electrodes 52 aretypically circular and can have diameters in the range of 1 to 10 mmwith specific embodiment of 2, 5 and 7 mm, larger sizes are alsocontemplated. They can comprise various conductive metals known in theart including gold, platinum, silver, stainless steel and alloysthereof. They are desirably positioned on the tissue contacting surface55 of assembly 50, but also may be recessed within the interior of theassembly so as to be capacitively coupled to the heart wall.

In preferred embodiments, the electrodes 52 of electrode assembly 50 areconfigured as bipolar electrodes. Such embodiments allow the depth ofelectrical energy delivered to myocardial tissue for purposes of pacingand cardioversion to be precisely controlled. However in alternativeembodiments, electrodes 52 can be configured as monopolar electrodeswith current flowing to a return electrode (not shown) positioned atanother location on lead 40 or another lead 20.

Electrode assembly 50 can be attached to the heart wall HW throughseveral different means. According to an embodiment shown in FIG. 6b ,the patch can include one or more attachment elements 57 that havetissue penetrating anchoring portions 57 a which penetrate and anchorinto the heart wall HW. Suitable attachment elements 57 can includevarious helical coils or barbed needles as is shown in FIG. 6b . Patch53 may also be attached to the heart wall through use of biocompatibleadhesives known in the art. In specific embodiments, the adhesive cancomprise thermally activated adhesives that are activated by heat fromflowing blood or electrical energy delivered from electrodes 52.

In various embodiments, lead 40 can include a plurality of electrodepairs 52/assemblies 50 which can be positioned in a distributedarrangement on the lead. In particular embodiments, the lead 40 caninclude between 2 to 10 pairs of electrodes with specific embodiments of3, 4, 5, 6, 7 and 8 electrode pairs. Greater and lesser numbers ofelectrode pairs also contemplated depending upon the size and shape ofatrial or ventricular chamber. The electrode pairs can be substantiallyequidistant from each with other spacing arrangements also contemplated.For example, particular spacing arrangements can be configured toaccount for the shape and size of a particular patient's atria which canbe determined by prior imaging of the patient's heart. In specificembodiments, the spacing between electrode pairs 52 can be in the rangefrom about 1 to about 5 cms with greater and lesser distances alsocontemplated.

Desirably, the spacing and number of electrodes pairs 52 on lead 40 orother lead are configured to allow the electrodes to sense theelectrical activity (e.g., the amount and time course of depolarization)of a selected area 60 of myocardial tissue MT within the atria orventricle. This in turn, allows for the generation of a conduction map61 of tissue area 60. Conduction map 60 can be used to detect for thepresence of one or more ectopic or other foci F of aberrant electricalactivity within area 60.

In various embodiments, electrode pairs 52 can be arranged in acircular, oval or other distributed pattern 62 around a selected area 60of the atrial or ventricular wall as is shown in the embodiments ofFIGS. 3 and 4. In particular embodiments, electrode pairs 52/assemblies50 are arranged in circular, oval or other pattern 62 around the SA nodeas is shown in the embodiment of FIG. 3 (desirably, the electrode pairs52 are positioned to be substantially equidistant from the SA node).Such embodiments allow for the detection of particular foci F causingpremature depolarization of the Atria by allowing comparison of theearliest depolarization within the entire area 60 (or adjacent to it) tothat of the SA node. As is described herein, software algorithmsresident 130 within pacemaker 10 can be used to detect the location LFof such foci F and then send a pacing signal to that location to takeconductive control of the Foci and prevent it from causing AF.

In addition to electrodes 52, lead 40 can also include other sensors 70for detection of various electrical and/or mechanical properties. Inparticular embodiments, sensors 70 can include an accelerometer 70, suchas a 3 axis accelerometer for detection of atrial or other heart wallmotion as is shown in the embodiment of FIG. 4. Similar to electrodes52, sensors 70 be arranged in selectable distributed pattern 62 on theendocardial or epicardial surface of the heart, such as a circular, ovalor other pattern.

Patch 53 will typically have an oval or other like shape, particularlyfor bipolar electrode embodiments, though other shapes are alsocontemplated. All or a portion of the patch can comprise variousbiocompatible polymers known in the art including PTFE, polyurethane,silicone and various other elastomers known in the. Desirably patch 53has sufficient flexibility to conform to shape of heart wall as well asbend and flex with the motion of the heart so as to remain attached tothe heart wall and not impede the motion of the heart wall. Patch 53 canalso include one or more biocompatible non-thrombogenic coatings 58 suchas silicone or other elastomeric coating. Coatings 58 can also have onemore drugs 58 d embedded in the coating, so as to be elutable over anextended period of time up to years. Drugs 58 d can include variouscompounds such as Taxol or compound known in the stent arts for reducingplatelet and cellular adhesion to the patch. Drugs 58 d can also includevarious antibiotics and antimicrobials such as vancomyacin, cefamandol,gentamicin and silver compounds for reducing the likelihood of bacterialadhesion and growth, or infection of patch 53. In some embodiments,patch 53 can have a multilayer construction, in these and relatedembodiments, coating 58 can comprise a layer 58 which will typically bea tissue contacting layer 58.

In various embodiments, all or a portion of patch 53 and/or electrodes52 can comprise a radio-opaque or echogenic material for visualizing alocation of assembly 50 and/or electrodes 52 in the heart underflouroscopy, ultrasound or other medical imaging modality. Suitableradio-opaque materials include platinum and titanium dioxide. Inparticular embodiments, patch 53 can include a marker section 59 madeout of such materials for visualizing the location of the electrode pair51. Desirably, marker 59 is centrally located on the patch so as to beequidistant from each electrode 52, to enable the physician to use themarker as a guide for placing the electrodes at a desired location onthe heart wall. Alternatively, marker 59 can be positioned on an edge ofpatch 53 as is shown in FIG. 6 a.

In use, markers 59 allow for the precise placement of the electrodeassemblies 50 along the endocardial wall of either the atria or theventricles so as to define the selectable area 60 of the heart formeasurement of electrical activity. For example, in particularembodiments the markers can be aligned with a superimposed image of analignment template that marks the desired location for each electrodeassembly. The markers also allow the physician to determine throughvarious cardiovascular imaging methods that the electrode assembliesremain attached to heart wall over time. Additionally, once an ectopicor other foci F of aberrant electrical activity has been detected, theycan be used as a point of reference for performing various RF ablativeprocedures to ablate the area of tissue responsible for the foci orotherwise create a conduction block around it.

Referring now to FIG. 7, pacemaker 10 can include various circuitry andother components. Some of the typical circuitry 110 and electronicdevices 120 in a pacemaker 10 or like device can include power controlcircuitry 111, amplification and sensing circuitry 112, pacing circuitry113, telemetry circuitry 114, micro-controller/micro-processor devices121 and memory devices 122. One or more software algorithms 130 can bestored in memory device 122 and/or processor 121 for implementation byprocessor 121. Such algorithms 130 can include cardiac mapping and focidetection algorithms, pacing algorithms (both atrial and ventricular),atrial fibrillation detection algorithms, ventricular fibrillationdetection algorithms, cardioversion algorithms (high and low voltage(e.g., 8 to 10 volts) and combinations thereof.

In embodiments of methods for positioning apparatus 30 in the body, thephysician can place the endocardial lead in the right atrium byadvancement from a percutaneous introductory site in the jugular vein ora related site. As described above, the desired positioning of theelectrode assemblies 50 in the atria can be achieved by imaging theheart during placement and observing the position of markers 59. Theepicardial leads can be placed using surgical techniques such as amini-thorocotomy or a minimally invasive procedure using endoscopy.Additional leads can be positioned as needed in the right or leftventricles using minimally invasive or surgical techniques. One or moreof these leads can be subsequently coupled to a pacemaker 10 positionedin the chest or other location.

In exemplary embodiments of methods for using the invention, system 5and atrially positioned leads 40 can be used to detect and treat atrialfibrillation in the following fashion. The distributed electrodeassemblies can be used to monitor the patient's EKG including the P waveas well as map conduction in the area within or adjacent thatcircumscribed by the electrode assemblies, preferably this area includesthe SA node. Atrial fibrillation can be detected based on theelimination or abnormality of the P wave as is shown in FIGS. 8b and 8c. When AF occurs, using the conduction map, the location of the ectopicor other foci causing the atrial fibrillation can be identified bylooking at the time course of depolarization and identifying locationsthat depolarize before the SA node. Cardioversion can then be performedas described below to return the heart to normal sinus rhythm.

After cardioversion is performed and the heart returned to normal sinusrhythm, the electrode assemblies nearest that foci can then be used tosend a pacing signal to that site and surrounding tissue to prevent thesite from causing another episode of atrial fibrillation. Also, thelocation of that site can be stored in memory of the pacemaker so thatnext time abnormal atrial depolarization is detected, a pacing signalcan be sent immediately to that site to prevent the occurrence of AF. Insome embodiments, a site of early activation can be paced continuously.Atrial pacing can be performed to produce a stimulated P wave, P_(s)which can be triggered off the R wave, R, or the R to R interval, R_(i)as is shown in FIGS. 8a and 8b with appropriate time adjustment Ta forfiring during the time period Tp when the normal P wave would beexpected to occur.

In addition to detection of foci and other early activation/abnormalconductions sites in the atria, atrial fibrillation can also be detectedusing an accelerometer 71 such as a 3-axes accelerometer placed on theatrial wall (either epdicardial or endocardial) to sense atrial wallmotion as is shown in the embodiment of FIG. 4. Such motion ispredictive of atrial fibrillation via the effects atrial fibrillationhas on atrial wall motion which typically flutter as a result. Thesignal from the accelerometer can be used to supplement the electricalsignals from the bipolar leads positioned on the left atria to increasethe predictive power of various algorithms used by the pacemaker for thedetection of AF. Additionally, sensory inputs from the accelerometer canalso be used to assess the effectiveness of atrial pacing signal inpreventing AF and/or returning the heart to normal sinus rhythm.

As described above, when an episode of atrial fibrillation has beendetected embodiments of the invention can also be used for performingcardioversion to convert the atria from a fibrillative state back tonormal sinus rhythm. In these and related embodiments, the pacemaker cansimultaneously send a higher voltage pacing signal (in the range of 8 to10 volts) to all or majority of the pairs of distributed electrodes tosimultaneously depolarize (also described herein as conductivelycapture) a large enough area of the atrial myocardium to stop theaberrant currents causing the atrial fibrillation. These voltages, whilehigher than those used for pacing to prevent AF, are much lower thanthose typically used during conventional internal cardio version (in thehundreds of volts) or external cardioverions (in the thousands ofvolts). Such lower voltages can be used because the stimulation isdelivered by a multipoint source (resulting in higher current densities)and to a much smaller area of the heart than during typical internal orexternal cardioversion. By using voltages lower than those typicallyused during internal or external cardioversion, the pain experienced bythe patient can be greatly reduced. The other benefit of this approachis that by using bipolar electrodes at each site, the electrical energydelivered to the heart can be contained to a relatively small region sothat the risk of stimulating the ventricles (an unwanted effect in thiscase) is very small. The voltage level for achieving cardioversion canbe adjusted based on one or more of the following factors (the“conversion voltage adjustment factors”): i) the size of the area oftissue bounded by distributed electrode pairs (smaller areas requireless voltage); ii) the location of the ectopic foci (the closer the focito a particular electrode pair the less the required voltage; iii) thenumber of foci (larger number of foci may require larger voltages); iv)the number of electrode pairs defining the area (the more electrodes thelower the voltage); and v) the number of prior episodes of AF (a largernumber of episodes may require higher voltage). One or more of thesefactors can be programmed into the algorithm resident within thepacemaker which controls the cardioverion process. Also the conversionalgorithm can programmed to use the lowest possible voltage at first,and then progressively increase it until conversion is achieved. Thevoltage which achieves conversion can then be stored in memory and usedagain as a starting point in a subsequent conversion attempt with tuningor fine tuning using one or more of the five conversion voltageadjustment factors described above.

CONCLUSION

The foregoing description of various embodiments of the invention hasbeen presented for purposes of illustration and description. It is notintended to limit the invention to the precise forms disclosed. Manymodifications, variations and refinements will be apparent topractitioners skilled in the art. For example, embodiments of theapparatus for detection and treatment of atrial arrhythmias andfibrillation can also be adapted for detection and treatment of variousventricular arrhythmias.

Elements, characteristics, or acts from one embodiment can be readilyrecombined or substituted with one or more elements, characteristics oracts from other embodiments to form numerous additional embodimentswithin the scope of the invention. Moreover, elements that are shown ordescribed as being combined with other elements, can, in variousembodiments, exist as standalone elements. Hence, the scope of thepresent invention is not limited to the specifics of the describedembodiments, but is instead limited solely by the appended claims.

What is claimed is:
 1. An apparatus for detection and treatment of cardiac arrhythmia, the apparatus comprising: an electrical lead having a proximal and distal portion, the distal portion configured to be positioned in a chamber of a heart, the proximal portion having an end configured to be coupled to a pacemaker device, the electrical lead comprising a plurality of conductive wires; a plurality of membrane patches distributed along the electrical lead, each membrane patch configured to be attached to a wall of the heart and to bend and flex with motion of the heart without impeding motion of the heart; and a plurality of pairs of electrodes, wherein at least one pair of electrodes is positioned on each membrane patch, the electrodes of each pair being (i) coupled to a conductive wire of the electrical lead, and (ii) configured to at least sense an electrical signal of the wall of the heart; and wherein the distribution of the plurality of membrane patches and electrode pairs along the electrical lead is configured to allow the plurality of electrode pairs to be distributed in a pattern on the wall of the heart, the pattern configured to i) detect a location of a foci of aberrant electrical activity located within or adjacent to an area, and ii) send a pacing signal to that location to prevent or stop an occurrence of fibrillation caused by that foci.
 2. The apparatus of claim 1, wherein the wall of the heart is an endocardial wall.
 3. The apparatus of claim 1, wherein the electrical lead has a mechanical property configured to allow the electrical lead to be advanced to the chamber from a percutaneous introductory site.
 4. The apparatus of claim 3, wherein the mechanical property is at least one of flexibility or pushability.
 5. The apparatus of claim 1, wherein the plurality of electrode pairs include eight pairs of electrodes.
 6. The apparatus of claim 1, wherein at least one of the electrode pairs includes a marker for visualizing a location of the electrode pair in the heart using a medical imaging modality.
 7. The apparatus of claim 1, wherein the plurality of electrode pairs are configured and arranged in a pattern defining an area to send a simultaneous signal to the area from all of the electrode pairs to depolarize the area so as to convert a fibrillative state of the heart to normal sinus rhythm.
 8. The apparatus of claim 1, wherein the pattern on the wall of the heart corresponds to a circular pattern.
 9. The apparatus of claim 1, wherein the pattern on the wall of the heart corresponds to a pattern defining an area containing a sino-atrial (SA) node.
 10. The apparatus of claim 9, wherein the pattern defining the area containing the sino-atrial (SA) node is arranged such that the electrode pairs are at selectable distances from the SA node so that the location of the foci of aberrant electrical activity can be determined relative to the SA node.
 11. The apparatus of claim 9, wherein the pattern defining the area containing the sino-atrial (SA) node is arranged such that the electrode pairs are substantially equidistant from the SA node so that the location of the foci of aberrant electrical activity can be determined relative to the SA node.
 12. The apparatus of claim 1, wherein the membrane comprises PTFE, silicone, polyurethane and/or polyester.
 13. The apparatus of claim 1, wherein the membrane comprises an attachment element for attaching the membrane to the wall of the heart.
 14. The apparatus of claim 13, wherein the attachment element comprises a barbed needle or a helical screw.
 15. The apparatus of claim 1, wherein the chamber of the heart is a ventricular chamber.
 16. The apparatus of claim 1, further comprising: an accelerometer coupled to at least one of the conductive wires, the accelerometer configured to be positioned on the wall of the heart and configured to sense motion of the wall of the heart.
 17. The apparatus of claim 16, wherein the accelerometer is configured to sense motion in three axes.
 18. A system configured to detect and treat cardiac arrhythmia, the system comprising: a pacemaker configured to be implanted; and the apparatus of claim 1, wherein at least one of the conductive wires is coupled to the pacemaker.
 19. The system of claim 18, wherein the pacemaker includes a controller, the controller including an algorithm that utilizes the plurality of electrode pairs to detect an onset of fibrillation based on detection of a location of an earliest depolarization occurring before that from the sino-atrial node.
 20. The system of claim 19, wherein the controller includes an algorithm configured to prevent the onset of fibrillation by sending a pacing signal to the location of the earliest depolarization. 